Wastewater heat exchanger

Abstract

A wastewater heat exchanger, including a housing, a tubing assembly, and a cleaning device. The tubing assembly includes cylindrical tubes arranged in parallel and below one another, and have heat-absorbing fluid flowing through them. The cleaning device, which is suspended from above the tubing assembly and is slidable along the longitudinal direction of the tubes, includes retaining elements depending from a support and hanging down between the tubes. The retaining elements have oppositely-directed elastic lips that sweep over the outer surface of laterally adjacent tubes, and each elastic lip includes a finger fixed to the retaining element at an angle (α) of 5 to 30° to the longitudinal direction of the tubes with the ends of the fingers curved in the longitudinal direction of the tubes, so that each finger is engaged between two vertically superimposed tubes, and adjacent fingers cover at least half of each outer tube surface.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to a fluid heat exchanger. More specifically, the present disclosure relates to a heat exchanger for wastewater, where the heat exchanger is disposed in a housing having an inlet and an outlet for wastewater, and includes jacketed cylindrical tubes through which a heat-absorbing fluid flows, and a cleaning device for the outer surfaces of the tubes.BACKGROUND

[0002] A wastewater heat exchanger is disclosed by DE 102 008 001 518 A1 that includes a cleaning device having substantially semicircular lips that are pressed onto the tube surface from opposing sides perpendicular to the respective tube axis, and that sweep across the outer tube surfaces and scrape off deposited dirt layers (biofilms, sewer membranes). The contact pressure of the lips is therefore greatest in the center of the semicircle but decreases towards the ends of the semicircle to zero, resulting in an uneven and unsatisfactory scraping effect. Furthermore, the ends of the lips that rest against the tubes deflect in the opposite direction of movement during the reciprocating motion of the cleaning device, which also impairs the scraping effect. Another disadvantage of the disclosed wastewater heat exchanger is that the support for the retaining elements for the scraper lips is mounted on rollers on rails running longitudinally along the tubes on both sides of the tube assembly, and the roller mechanism requires a separate drive to create a reciprocating motion. This entire mechanism is located above the water's surface because it must be protected from contamination due to its moving parts and consequently requires a relatively large amount of space.

[0003] What is needed is therefore a wastewater heat exchanger that overcomes the disadvantages of the DE 102 008 001 518 A1 heat exchanger, and is capable of a reliable and complete cleaning of the exchange tube surfaces while nonetheless having a compact design.SUMMARY

[0004] The present disclosure is directed to wastewater heat exchangers, the heat exchangers including an assembly of a plurality of cylindrical tubes within a housing, with heat-absorbing fluid flowing through the tubing assembly, and a cleaning device that is configured to sweep over the outer surfaces of the cylindrical tubes.

[0005] In one example, the wastewater heat exchangers of the present disclosure include a housing, the housing including a wastewater inlet and a wastewater outlet; and a tubing assembly within the housing, where a heat-absorbing fluid flows through the tubing assembly. The tubing assembly includes a plurality of cylindrical tubes arranged in parallel and below one another in a substantially cuboid arrangement, with each cylindrical tube having an outer surface. The wastewater heat exchangers further include a cleaning device for the outer tube surfaces that is suspended from above the tubing assembly so that the cleaning device is slidable in a longitudinal direction of the cylindrical tubes; where the cleaning device includes retaining elements that depend from a support that is connected to a single guide extending in the longitudinal direction of the cylindrical tubes, so that the retaining elements hang down between the cylindrical tubes. Each retaining element has at least two oppositely-directed elastic lips attached to the retaining element so that the at least two elastic lips are configured to sweep over the outer tube surfaces of laterally adjacent cylindrical tubes, and each elastic lip further includes a finger that is fixed in the retaining element at an angle (α) of 5 to 30° to the longitudinal direction of the cylindrical tubes with the ends of the fingers being curved in the longitudinal direction of the cylindrical tubes, so that each finger is engaged between two vertically superimposed cylindrical tubes, and adjacent fingers cover at least half of each outer tube surface.

[0006] The features, functions, and advantages of the disclosed wastewater heat exchangers may be achieved independently in various embodiments of the present disclosure, or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a front view of an illustrative wastewater heat exchanger according to the present disclosure with the cover and front wall of the housing removed.

[0008] FIG. 2 top view of the wastewater heat exchanger of FIG. 1 with the housing cover removed.

[0009] FIG. 3 is an oblique view of the wastewater heat exchanger of FIGS. 1 and 2 without a cover or a front wall.

[0010] FIG. 4 is an oblique view of the wastewater heat exchanger of FIGS. 1 and 2 including a cover and a front wall.

[0011] FIG. 5 shows an enlarged detail A as indicated in FIG. 1.

[0012] FIG. 6 shows an enlarged detail B as indicated in FIG. 2.

[0013] FIG. 7 shows an oblique view of enlarged detail A shown in FIG. 5.

[0014] FIG. 8 shows an enlarged oblique view of a portion of the tube assembly of the wastewater heat exchanger of FIG. 3.

[0015] FIG. 9 shows a top cutaway view of the lip band of the wastewater heat exchanger of FIG. 3.

[0016] FIG. 10 shows an enlarged detail C as indicated in FIG. 1.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0017] The wastewater heat exchangers of the present disclosure provide reliable and complete cleaning of the outer surfaces of heat exchange tube surfaces while having a compact design. These advantageous properties are achieved by virtue of the construction of the heat exchanger cleaning device, in which each elastic lip has a finger engaging between two superimposed tubes and is fixed in the cleaning device retaining element at an angle of 5 to 30° to the longitudinal direction of the tubes, whereby adjacent fingers cover at least half a tube surface and the ends of the fingers are curved in the longitudinal direction of the tubes, and that in each retaining element two oppositely directed lips are attached, which each sweep over laterally adjacent tubes, and that the support of the retaining elements is connected to a single guide extending in the longitudinal direction of the tubes.

[0018] Because the elastic lips engage with their fingers between the tubes at an angle of 5 to 30°, they don't strike the tube surface perpendicularly, instead conforming to the respective tube surfaces in a slightly curved, tensioned position during use. This constant pressure on the tube surface ensures that any dirt buildup on the surface is reliably removed. This is further enhanced by the fact that adjacent fingers encompass at least half of the outer tube surface, ensuring that no part of the tube surface remains untouched by a finger. Due to the lips pointing in opposite directions in pairs, the fingers resting on the tube surfaces are subjected to pressure and friction depending on the direction of movement of the cleaning device, once under pressure and once under tension, but always with a so far unprecedented contact force that ensures the complete removal of all deposits from the tubes. Finally, the movability of the cleaning device, i.e., the support for the retaining elements, on just a single guide allows for a compact design, even in greywater environments. The susceptibility to movement blockage of the cleaning device is therefore minimized.

[0019] For ease of installation, it is advantageous to combine several elastic lips into a common elastic lip band, with the distance between adjacent fingers corresponding to 1.25 to 2.0 times the outer diameter of the tubes. This distance, measured from finger center to finger center, ensures optimal twisting and conforming of the elastic fingers to the tube surface when installed. For the same purpose, it is beneficial if the length of the fingers corresponds to 2 to 3.25 times the outer diameter of the tubes. Furthermore, for the scraping process, it has proven effective if the width of the fingers at their free end corresponds to 0.25 to 1.0 times the outer diameter of the tubes.

[0020] In order to improve the elasticity and conformability of the fingers, and thus their scraping action, it has proven advantageous for each finger to have a longitudinal slot whose length corresponds to 0.5 to 3 times and whose width to 0.05 to 0.4 times the outer diameter of the tubes. The adaptability of the fingers to the tube surface is further improved if each lip at the base of the finger includes least one recess.

[0021] To secure the elastic lips or elastic lip bands pointing in opposite directions, it has proven effective to have the retaining elements feature clamping strips between which they are held. This greatly simplifies the replacement of worn lips or lip bands with new ones.

[0022] A particular advantage is that the support of the retaining elements is no longer supported on both sides of the tube assembly by rollers running in guide rails, but that the guide of the support of the retaining elements consists of a stationary, rotatably mounted threaded spindle that passes through a threaded nut connected to the support. Depending on the direction of rotation of the threaded spindle, the support for the retaining elements, and thus the cleaning device, can be moved back and forth along the tube assembly. Anchoring the support with the threaded nut on the threaded spindle is sufficient in itself, as the retaining elements hanging between the tubes are stabilized in every position of movement by the fingers that sweep over the tubes. The threaded spindle-threaded nut drive system can even come into contact with greywater without risk of jamming and requires no additional bearings. However, it is advantageous to provide sliding bearings surrounding the threaded spindle on both sides of the threaded nut, preferably with a plastic sliding layer. For a plastic sliding layer offers good dry-running properties and resistance to chemicals and wastewater. In this case, therefore, neither lubrication of the bearings nor sealing against grey water is required.

[0023] When sliding bearings are present on both sides of the threaded nut, it has been found that their length should each be approximately 1 / 10 of the tube length. This is because, with typical dimensions of wastewater heat exchangers (approximately 2.6 m long, 0.82 m high, and 1.6 m high), the point of force application when the support is moved is located roughly halfway up the retaining elements, making the bearing length of the sliding bearings statically and dynamically optimal.

[0024] To ensure a rigid connection between the support and the sliding bearings, it is advantageous if each sliding bearing is supported by a strut on the support. Ideally, the strut should form an angle of approximately 30° with the sliding bearing.

[0025] The wastewater heat exchangers of the present disclosure are explained in greater detail below with reference to an exemplary and preferred embodiment depicted in the accompanying drawings.

[0026] A wastewater heat exchanger 1 is shown in FIGS. 1 to 4, the heat exchanger including a housing 2 with an inlet 3 (in FIG. 4, two connections of the inlet 3 are shown) and an outlet 4 for wastewater. The outlet 4 extends upwards from the bottom of the housing 2, which also contains a cleaning drain 5, to the level of a safety overflow 6.

[0027] Housing 2 accommodates a substantially cuboid package 7 of cylindrical tubes 8 arranged parallel to and below one other and connected in a serpentine manner, through which a heat-absorbing fluid, for example a brine, flows, which is supplied and removed via fluid connections 9.

[0028] The housing 2 contains a cleaning device for the outer surfaces 23, or jackets, of the tubes 8. This device is suspended above the tube assembly 7 so as to be slidable in the longitudinal direction of the tubes 8 and has retaining elements 11 hanging from a support 10 between the tubes 8, which carry elastic lips 12 that sweep over the tube surfaces 23.

[0029] The movable suspension is ensured by a single guide extending longitudinally along the tubes 8 in the form of a stationary, rotatably-mounted threaded spindle 14 equipped with a drive 13 and a threaded nut 15 encompassing this spindle and connected to the support 10 (see in particular FIG. 10). The threaded spindle 14 is provided, for example, with a drive thread, preferably a trapezoidal thread. As can be seen from FIGS. 5 to 9, each lip 12 has a finger 16 engaging between two superimposed tubes 8 and is fixed in the retaining element 11 at an angle α of 5 to 30° relative to the longitudinal direction of the tubes 8. Adjacent fingers 16 each encompass at least half of the tube surface 23, and the ends of the fingers 16 are bent in the longitudinal direction of the tubes 8. This is most clearly shown in FIG. 6: Without contact with the tubes 8, the lips 12, including the fingers 16, would assume the position indicated by the dashed lines; however, in contact with the tubes 8, they are held against them under tension with a twisting motion. This is a significant advantage and improvement over the prior art, as it achieves an optimal scraping effect on the dirt deposits covering the tube jackets. Two lips 12 pointing in opposite directions are attached to each retaining element 11, each sweeping over laterally adjacent tubes 8, as is most clearly shown in FIGS. 6 and 8. Since the fingers 16 each encompass at least half the circumference of a tube, each tube 8 is completely scraped during a back-and-forth movement of the cleaning device, with the fingers 16 being either slightly compressed or slightly stretched depending on the direction of movement: i.e., their arc of curvature is sometimes reduced and sometimes lengthened. However, in every direction of movement, the lips 12 and fingers 16 make full contact with the respective tube surface 23, thus ensuring the safe scraping of any coating.

[0030] As can be seen in FIG. 9, several elastic lips 12 can be combined into a common elastic lip band 17, which simplifies assembly and disassembly in a cost-effective manner. The elastic lips 12 and elastic lip bands 17 are made of an elastic material, for example PE or PP, with heat-and corrosion-resistance suitable for the respective application. In tests, it proved advantageous to dimension the distance a between adjacent fingers 16 to 1.25 to 2.10 times the outer diameter of the tubes 8. For the length l of the fingers 16, 2 to 3.25 times the outer diameter of the tubes 8 has proven effective. For the width b of the fingers 16 at the free finger end, an optimum was found to be 0.25 to 1.0 times the outer diameter of the tubes 8.

[0031] To allow the fingers 16 to fit snugly between adjacent tubes 8 without jamming, they are provided with a longitudinal slot 18 that promotes their flexibility. The length of this slot corresponds to 0.5 to 3.0 times the outer diameter of the tubes 8, and the width to 0.05 to 0.4 times. To increase flexibility, each lip 12 has at least one recess 19 at the base of the finger 16. FIGS. 5, 7, and 9 illustrate two such recesses 19 each.

[0032] As can be seen in FIGS. 6 and 8, each retaining element 11 has clamping strips 20 between which the elastic lips 12 or elastic lip bands 17, pointing in opposite directions, are received. The replacement of worn elastic lips 12 or elastic lip bands 17 can thus be carried out in a highly efficient manner.

[0033] Although the threaded nut 15 is sufficient for guiding the support 10 of the retaining elements 11 on the threaded spindle 14, it is more advantageous to provide sliding bearings 21 on both sides of the threaded nut 15, which better support the cleaning device during its reciprocating movement on the threaded spindle 14. This is because the point of application of the resulting force on the support 10 and the retaining elements 11 is located approximately halfway up the housing 2, which generates a torque that must be absorbed by the sliding bearings 21 and the threaded nut 15. Preferably, the sliding bearings 21 are provided with a chemically resistant plastic coating, so that, on the one hand, no separate lubrication is required, and on the other hand, the entire moving unit (threaded spindle 14, threaded nut 15, sliding bearings 21) can come into contact with the wastewater.

[0034] Based on experience with a prototype, the longitudinal extent of each sliding bearing 21 is approximately 1 / 10 of the length of the tubes 8. To support the fastening of the sliding bearings 21 to the threaded nut 15, both are supported on the support 10 by a strut 22, whereby it is recommended that each strut 22 forms an angle of approximately 30° with the associated sliding bearing 21.

[0035] During operation, warm or hot wastewater enters the housing 2 through the inlet 3, flows around the tubes 8 of the tube assembly 7, and exits as cold wastewater through the outlet 4; in the event of a blockage, it can also escape through the safety overflow 6. The fluid flowing through the tubes 8 absorbs the heat of the wastewater and transfers it to the service unit via the fluid connections 9. Depending on the degree of contamination of the wastewater, the cleaning device is activated at certain intervals by the drive 13, by rotating the threaded spindle 14. This causes the threaded nut 15, along with the attached support 10 with retaining elements 11 and elastic lips 12 (or elastic lip bands 17), to move back and forth depending on the direction of rotation. The fingers 16, which grip the outer tube surfaces 23, are subjected to both tensile and shear stresses, reliably scraping the tube surfaces 23. The scraped-off tube deposits that sink to the bottom are removed through cleaning drain 5.

[0036] An illustrative wastewater heat exchanger according to the present disclosure can, for example, have the following specifications:

[0037] Dimension: 2.6 m×0.82 m×1.6 m

[0038] Nominal heat exchanger surface area: 32 m2

[0039] Wastewater volume: 2-15 m3 / h

[0040] Wastewater temperature: 10-100° C.

[0041] Power: 10-200 KWAt this size, housing 2 can be made of plastic. Larger modules are typically housed in concrete containers. It is, of course, possible to combine several modules or accommodate them in a single housing. In one embodiment the cleaning device is suspended by means of a threaded nut on a threaded spindle, the drive of which is located outside the housing, and that elastic lips are provided for scraping the tube jackets, which are positioned at an angle to the tube axis and whose fingers grip the tube jackets.Selected Illustrative Embodiments

[0042] This section describes additional aspects and features of selected wastewater heat exchangers of the present disclosure, presented without limitation as a series of paragraphs, some or all of which may be alphanumerically designated for clarity and efficiency. Each of these paragraphs can be combined with one or more other paragraphs, and / or with disclosure from elsewhere in this application, in any suitable manner. Some of the paragraphs below expressly refer to and further limit other paragraphs, providing without limitation examples of some of the suitable combinations.

[0043] A1. Wastewater heat exchanger (1) comprising, in a housing (2) with inlet and outlet (3, 4) for the wastewater, a substantially cuboid package (7) of cylindrical tubes (8) arranged parallel to and below one another and through which a heat-absorbing fluid flows, and a cleaning device for the tube jackets, which is suspended above the tube package (7) slidably in the longitudinal direction of the tubes (8) and is provided with retaining elements (11) hanging down between the tubes (8) from a support (10), which carry elastic lips (12) that sweep over the tube jackets, characterized in that each lip (12) has a finger (16) engaging between two superimposed tubes (8) and is fixed in the retaining element (11) at an angle (α) of 5 to 30° to the longitudinal direction of the tubes (8), whereby adjacent fingers (16) cover at least half a tube jacket and the ends of the fingers (16) are curved in the longitudinal direction of the tubes (8), and that in each retaining element (11) two oppositely directed lips (12) are attached, which each sweep over laterally adjacent tubes (8), and that the support (10) of the retaining elements (11) is connected to a single guide extending in the longitudinal direction of the tubes (8).

[0044] A2. Wastewater heat exchanger (1) according to paragraph A1, characterized in that several lips (12) are combined to form a common lip band (17), wherein the distance (a) between adjacent fingers (16) corresponds to 1.25 to 2.0 times the outer diameter of the tubes (8).

[0045] A3. Wastewater heat exchanger (1) according to paragraph A1 or A2, characterized in that the length (l) of the fingers (16) corresponds to 2 to 3.25 times the outer diameter of the tubes (8).

[0046] A4. Wastewater heat exchanger (1) according to one of paragraphs A1 to A3, characterized in that the width (b) of the fingers (16) at the free finger end corresponds to 0.25 to 1.0 times the outer diameter of the tubes (8).

[0047] A5. Wastewater heat exchanger (1) according to one of paragraphs A1 to A4, characterized in that each finger (16) has a longitudinal slot (18) whose length corresponds to 0.5 to 3 times and whose width corresponds to 0.05 to 0.4 times the outer diameter of the tubes (8).

[0048] A6. Wastewater heat exchanger (1) according to one of paragraphs A1 to A5, characterized in that each lip (12) has at least one recess (19) at the base of the finger (16).

[0049] A7. Wastewater heat exchanger (1) according to one of paragraphs A1 to A6, characterized in that each retaining element (11) has clamping strips (20) between which the lips (12) pointing in opposite directions are received.

[0050] A8 Wastewater heat exchanger (1) according to one of paragraphs A1 to A7, characterized in that the guide of the support (10) of the retaining elements (11) consists of a stationary, rotatably mounted threaded spindle (14) which passes through a threaded nut (15) connected to the support (10).

[0051] A9. Wastewater heat exchanger (1) according to paragraph A8, characterized in that sliding bearings (21) surrounding the threaded spindle (14) are provided on both sides of the threaded nut (15), preferably with a plastic sliding layer.

[0052] A10. Wastewater heat exchanger (1) according to paragraph A9, characterized in that the longitudinal extent of each sliding bearing (21) corresponds to approximately 1 / 10 of the length of the tubes (8).

[0053] A11. Wastewater heat exchanger (1) according to paragraph A9 or A10, characterized in that each sliding bearing (21) is supported on the support (10) by a strut (22).

[0054] A12. Wastewater heat exchanger (1) according to paragraph A11, characterized in that the strut forms an angle of approximately 30° with the sliding bearing (21).

[0055] In the description and claims, the terms “substantially” or “essentially” mean a deviation of up to 10% of the specified value, if physically possible, both downwards and upwards, otherwise only in the meaningful direction; in the case of degree specifications (angle and temperature), this means ±10°.

[0056] All quantities and proportions, in particular those used to define and / or claim the invention, unless they relate to specific examples, are to be understood with a tolerance of ±10%: 11%, for example, means from 9.9% to 12.1%. In phrases such as “a solvent,” or “one spring,” the words “a” and “one” should not to be construed as a numeral or numeric value, but as an indefinite article or pronoun, unless the context indicates otherwise.

[0057] Unless otherwise specified, the term “combination” or “combinations” refers to all types of combinations, from two of the components in question to a plurality or all such components; the terms “having,”“including,” and “containing” should be construed as non-limiting and having an equivalent meaning to “comprising.”

[0058] The characteristics and variants specified for the individual embodiments and examples disclosed herein may be freely combined with those of the other examples and embodiments and may in particular be used to characterize the heat exchanger of the present disclosure in the claims without necessarily entraining the other details of the respective embodiment or the respective example.Listing of Reference Numerals1 Wastewater heat exchanger

[0060] 2 Housing

[0061] 3 Inlet

[0062] 4 Outlet

[0063] 5 Cleaning drain

[0064] 6 Safety overflow

[0065] 7 Tube assembly

[0066] 8 Tube

[0067] 9 Fluid connection

[0068] 10 Support

[0069] 11 Retaining element

[0070] 12 Elastic lip

[0071] 13 Drive (of 14)

[0072] 14 Threaded spindle

[0073] 15 Threaded nut

[0074] 16 Finger

[0075] 17 Elastic lip band

[0076] 18 Longitudinal slot

[0077] 19 Recess

[0078] 20 Clamping strip

[0079] 21 Sliding bearing

[0080] 22 Strut

[0081] 23 Outer surface of tube

Claims

1. A wastewater heat exchanger comprising:a housing, the housing including a wastewater inlet and a wastewater outlet; anda tubing assembly within the housing, wherein a heat-absorbing fluid flows through the tubing assembly, the tubing assembly includes a plurality of cylindrical tubes arranged in parallel and below one another in a substantially cuboid arrangement, each cylindrical tube having an outer surface; anda cleaning device for the outer tube surfaces that is suspended from above the tubing assembly so that the cleaning device is slidable in a longitudinal direction of the cylindrical tubes; whereinthe cleaning device includes retaining elements that depend from a support that is connected to a single guide extending in the longitudinal direction of the cylindrical tubes, so that the retaining elements hang down between the cylindrical tubes;each retaining element has at least two oppositely-directed elastic lips attached to the retaining element such that the at least two elastic lips are configured to sweep over the outer tube surfaces of laterally adjacent cylindrical tubes; andeach elastic lip further includes a finger having an end where the finger is fixed in the retaining element at an angle (α) of 5 to 30° to the longitudinal direction of the cylindrical tubes with the ends of the fingers being curved in the longitudinal direction of the cylindrical tubes, so that each finger is engaged between two vertically superimposed cylindrical tubes, and adjacent fingers cover at least half of each outer tube surface.

2. The wastewater heat exchanger according to claim 1, wherein a plurality of elastic lips in combination form a common elastic lip band; and a distance (a) between adjacent fingers is 1.25 to 2.0 times an outer diameter of the cylindrical tubes.

3. The wastewater heat exchanger according to claim 1, wherein a length (l) of the fingers is 2 to 3.25 times an outer diameter of the cylindrical tubes.

4. The wastewater heat exchanger according to claim 1, wherein a width of each finger at the end of the finger is 0.25 to 1.0 times an outer diameter of the cylindrical tubes.

5. The wastewater heat exchanger according to claim 1, wherein each finger defines a longitudinal slot having a length that is 0.5 to 3 times an outer diameter of the cylindrical tubes and having a width that is 0.05 to 0.4 times the outer diameter of the cylindrical tubes.

6. The wastewater heat exchanger according to claim 1, each elastic lip defines at least one recess disposed at a base of the finger.

7. The wastewater heat exchanger according to claim 1, wherein each retaining element includes a plurality of clamping strips, between which the oppositely-directed elastic lips are secured.

8. The wastewater heat exchanger according to claim 1, wherein the guide for the support of the retaining elements includes a stationary, rotatably-mounted threaded spindle that passes through a threaded nut that is connected to the support.

9. The wastewater heat exchanger according to claim 8, wherein the support further includes sliding bearings that surround the threaded spindle on both sides of the threaded nut.

10. The wastewater heat exchanger according to claim 9, wherein the sliding bearings include a plastic sliding layer.

11. The wastewater heat exchanger according to claim 9, wherein each sliding bearing extends longitudinally to an extent that corresponds to approximately 1 / 10 of a length of the cylindrical tubes.

12. The wastewater heat exchanger according to claim 9, wherein each sliding bearing is supported on the support by a strut.

13. The wastewater heat exchanger according to claim 12, wherein each strut forms an angle of approximately 30° with the sliding bearing that it supports.

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